Radiolabeled compounds have long been used in diagnostic and therapeutic procedures. Some radio metals have superior properties for use in these procedures. Technetium-99m (Tc-99m) is an ideal radionuclide for scintigraphic imaging because of its radioactive decay properties. It has a single photon energy of 140 keV, a half life of about 6 hours, and it is readily available from a .sup.99 Mo-.sup.99m Tc generator.
There is a large family of polyhydric complexes of technetium, with and without carboxylic acid groups, which differ widely in stability. Hwang, et al., Intl. J. of Appl. Radiat. Isot., 36 (6): 475-480 (1975). Hydroxycarboxylates tend to form soluble complexes with transition metals. Technetium (Tc) complexes of these compounds have been used for the nuclear imaging of kidneys, brain, myocardial infarcts and tumors. Russell and Speiser, J. Nucl. Med., 21: 1086-1090 (1980). .sup.99m Tc-D-glucoheptonate is the most widely used imaging agent. It has been used for brain and kidney imaging. Waxman, et al., J. Nucl. Med., 17: 345-348 (1976) and Arnold, et al., J. Nucl. Med., 16: 357-367 (1975). See also, Adler, et al., U.S. Pat. No. 4,027,005. However, .sup.99m Tc-D-glucoheptonate has been less successful as an imaging agent for myocardial infarct. Rossman, et al., J. Nucl. Med., 16: 980-985 (1975).
Much effort has been directed toward evaluating the usefulness of various radionuclides and radiopharmaceuticals for imaging myocardial tissue. Since the widespread use of surgery to treat coronary artery disease, accurate detection of perioperative myocardial infarction has become critical for the objective evaluation of operation results, especially of surgical patients who are at a high risk for myocardial necrosis. Perioperative infarction has been cited as a major cause of operative death and postoperative cardiac failure. Roberts, et al., J. of Surgical Research, 25:83-91 (1978). Myocardial imaging agents offer an effective, non-invasive method to detect myocardial infarct in these patients.